Atmospheric Pressure Higher altitudes have a lower pressure. There is less air above you. Lower altitudes have a higher pressure. There is more air above you. Sea level = 1 ATM of pressure (14.7 lbs/in2)
Pressures Under Water Pressure increases with water depth. Air and water above you exert a pressure. For every 33 ft (10 m) of depth, pressure increases by 1 ATM (14.7 lbs/in2).
Practice #1. On the top of the tallest mountain in the U.S. (Denali/Mt. McKinely) the air pressure is ½ the pressure found at sea level. What is the air pressure on top of Denali? Pressure = 14.7 lbs/in2 Pressure = 14.7 lbs/in2 2 Pressure = 7.35 lbs/in2
#2. A scuba diver dives to a depth of 66 feet. How many atmospheres of pressure are exerted on the scuba diver? 0 ATM at boundary of space and Earth’s atmosphere 1 ATM at sea level 2 ATM at 33 feet 3 ATM at 66 feet
#3. What is the atmospheric pressure on a scuba diver at 3 ATM? 1 ATM = 14.7 lbs/in2 Pressure = 14.7 lbs/in2 X 3 Pressure = 44.1 lbs/in2
Risks to Humans Low Pressures: High Pressures: The Bends- nitrogen bubbles in blood Altitude sickness- little oxygen to breathe Helicopters have a hard time flying